The invention relates generally to digital data processing, and more particularly, to digital data processing associated with on-screen displays.
Many conventional on-screen display (OSD) techniques disadvantageously require high resolution processing for an entire screen if any part of the screen requires high resolution processing. For example, Table 1 shows the number of bytes required to store a full screen picture 720 pixelsxc3x97576 lines in different display modes for an OSD system that does not allow mixing of several modes of display in real time on the same screen. When one part of the screen requires 256 colors, the full screen must be 256 colors, even if another part of the screen requires only 2 colors.
The present invention provides for on-screen display with a variable resolution capability that advantageously permits respective parts of a screen to be processed according to their respective resolution requirements, thereby reducing the processing power and memory required to produce the on-screen display. In particular, for any active window in the on-screen display, the invention can determine the data format used in memory to represent the pixels of that window, thereby permitting the window resolution to vary from window to window.